Simultaneous Whole-Body PET/MR Imaging in Comparison to PET/CT in Pediatric Oncology: Initial Results

Published Online:https://doi.org/10.1148/radiol.14131732

Our initial results suggest that PET/MR imaging is a promising imaging modality for pediatric oncology; it has intrinsically low radiation exposure and should be considered for pediatric patients wherever available.

Purpose

To compare positron emission tomography (PET)/magnetic resonance (MR) imaging and PET/computed tomography (CT) for lesion detection and interpretation, quantification of fluorine 18 (18F) fluorodeoxyglucose (FDG) uptake, and accuracy of MR-based PET attenuation correction in pediatric patients with solid tumors.

Materials and Methods

This prospective study had local ethics committee and German Federal Institute for Drugs and Medical Devices approval. Written informed consent was obtained from all patients and legal guardians. Twenty whole-body 18F-FDG PET/CT and 18F-FDG PET/MR examinations were performed in 18 pediatric patients (median age, 14 years; range, 11–17 years). 18F-FDG PET/CT and 18F-FDG PET/MR data were acquired sequentially on the same day for all patients. PET standardized uptake values (SUVs) were quantified with volume of interest measurements in lesions and healthy tissues. MR-based PET attenuation correction was compared with CT-derived attenuation maps (µ-maps). Lesion detection was assessed with separate reading of PET/CT and PET/MR data. Estimates of radiation dose were derived from the applied doses of 18F-FDG and CT protocol parameters. Descriptive statistical analyses were performed to report correlation coefficients and relative deviations for comparison of SUVs, rates of lesion detection, and percentage reductions in radiation dose.

Results

PET SUVs showed strong correlations between PET of PET/CT (PETCT) and PET of PET/MR (PETMR) (r > 0.85 for most tissues). Apart from drawbacks of MR-based PET attenuation correction in osseous structures and lungs, similar SUVs were found on PET images corrected with CT-based µ-maps (13.1% deviation of SUVs for bone marrow and <5% deviation for other tissues). Lesion detection rate with PET/MR imaging was equivalent to that with PET/CT (61 areas of focal uptake on PETMR images vs 62 areas on PETCT images). Advantages of PET/MR were observed especially in soft-tissue regions. Furthermore, PET/MR offered significant dose reduction (73%) compared with PET/CT.

Conclusion

Pediatric oncologic PET/MR is technically feasible, showing satisfactory performance for PET quantification with SUVs similar to those of PET/CT. Compared with PET/CT, PET/MR demonstrates equivalent lesion detection rates while offering markedly reduced radiation exposure. Thus, PET/MR is a promising modality for the clinical work-up of pediatric malignancies.

© RSNA, 2014

Online supplemental material is available for this article.

References

  • 1. Chen Z, Li X, Li F, Ouyang Q, Yu T. Evolving role of 18F-FDG-PET/CT for the body tumor and metastases in pediatrics. Eur J Radiol 2010;75(3):329–335.
  • 2. Miller E, Metser U, Avrahami G, et al. Role of 18F-FDG PET/CT in staging and follow-up of lymphoma in pediatric and young adult patients. J Comput Assist Tomogr 2006;30(4):689–694.
  • 3. Kaste SC. PET-CT in children: where is it appropriate? Pediatr Radiol 2011;41(Suppl 2):509–513.
  • 4. Ricard F, Cimarelli S, Deshayes E, Mognetti T, Thiesse P, Giammarile F. Additional Benefit of F-18 FDG PET/CT in the staging and follow-up of pediatric rhabdomyosarcoma. Clin Nucl Med 2011;36(8):672–677.
  • 5. Samuel AM. PET/CT in pediatric oncology. Indian J Cancer 2010;47(4):360–370.
  • 6. Franzius C. FDG-PET/CT in pediatric solid tumors. Q J Nucl Med Mol Imaging 2010;54(4):401–410.
  • 7. Kleis M, Daldrup-Link H, Matthay K, et al. Diagnostic value of PET/CT for the staging and restaging of pediatric tumors. Eur J Nucl Med Mol Imaging 2009;36(1):23–36.
  • 8. Tatsumi M, Miller JH, Wahl RL. 18F-FDG PET/CT in evaluating non-CNS pediatric malignancies. J Nucl Med 2007;48(12):1923–1931.
  • 9. Rhodes MM, Delbeke D, Whitlock JA, et al. Utility of FDG-PET/CT in follow-up of children treated for Hodgkin and non-Hodgkin lymphoma. J Pediatr Hematol Oncol 2006;28(5):300–306.
  • 10. Goo HW, Choi SH, Ghim T, Moon HN, Seo JJ. Whole-body MRI of paediatric malignant tumours: comparison with conventional oncological imaging methods. Pediatr Radiol 2005;35(8):766–773.
  • 11. Schaefer JF, Kramer U. Whole-body MRI in children and juveniles [in German]. Rofo 2011;183(1):24–36.
  • 12. Ley S, Ley-Zaporozhan J, Schenk JP. Whole-body MRI in the pediatric patient. Eur J Radiol 2009;70(3):442–451.
  • 13. Krohmer S, Sorge I, Krausse A, et al. Whole-body MRI for primary evaluation of malignant disease in children. Eur J Radiol 2010;74(1):256–261.
  • 14. Daldrup-Link HE, Franzius C, Link TM, et al. Whole-body MR imaging for detection of bone metastases in children and young adults: comparison with skeletal scintigraphy and FDG PET. AJR Am J Roentgenol 2001;177(1):229–236.
  • 15. Punwani S, Taylor SA, Bainbridge A, et al. Pediatric and adolescent lymphoma: comparison of whole-body STIR half-Fourier RARE MR imaging with an enhanced PET/CT reference for initial staging. Radiology 2010;255(1):182–190.
  • 16. Histed SN, Lindenberg ML, Mena E, Turkbey B, Choyke PL, Kurdziel KA. Review of functional/anatomical imaging in oncology. Nucl Med Commun 2012;33(4):349–361.
  • 17. Knopp MV, von Tengg-Kobligk H, Choyke PL. Functional magnetic resonance imaging in oncology for diagnosis and therapy monitoring. Mol Cancer Ther 2003;2(4):419–426.
  • 18. Schwenzer NF, Schraml C, Müller M, et al. Pulmonary lesion assessment: comparison of whole-body hybrid MR/PET and PET/CT imaging—pilot study. Radiology 2012;264(2):551–558.
  • 19. Drzezga A, Souvatzoglou M, Eiber M, et al. First clinical experience with integrated whole-body PET/MR: comparison to PET/CT in patients with oncologic diagnoses. J Nucl Med 2012;53(6):845–855.
  • 20. Stauss J, Franzius C, Pfluger T, et al. Guidelines for 18F-FDG PET and PET-CT imaging in paediatric oncology. Eur J Nucl Med Mol Imaging 2008;35(8):1581–1588.
  • 21. Delso G, Fürst S, Jakoby B, et al. Performance measurements of the Siemens mMR integrated whole-body PET/MR scanner. J Nucl Med 2011;52(12):1914–1922.
  • 22. Klein S, Staring M, Murphy K, Viergever MA, Pluim JP. Elastix: a toolbox for intensity-based medical image registration. IEEE Trans Med Imaging 2010;29(1):196–205.
  • 23. Bongartz G, Golding SJ, Jurik AG, et al. European Guidelines for Multislice Computed Tomography. Luxenbourg: European Commission, 2004.
  • 24. American Association of Physicists in Medicine. Size-specific dose estimates (SSDE) in pediatric and adult body CT examinations. (Task Group 204). College Park, Md: American Association of Physicists in Medicine, 2011.
  • 25. Radiation dose to patients from radiopharmaceuticals (addendum 2 to ICRP publication 53). Ann ICRP 1998;28(3):1–126.
  • 26. Pfluger T, Melzer HI, Mueller WP, et al. Diagnostic value of combined 18F-FDG PET/MRI for staging and restaging in paediatric oncology. Eur J Nucl Med Mol Imaging 2012;39(11):1745–1755.
  • 27. Kumar J, Seith A, Kumar A, et al. Whole-body MR imaging with the use of parallel imaging for detection of skeletal metastases in pediatric patients with small-cell neoplasms: comparison with skeletal scintigraphy and FDG PET/CT. Pediatr Radiol 2008;38(9):953–962.
  • 28. Bezrukov I, Mantlik F, Schmidt H, Schölkopf B, Pichler BJ. MR-Based PET attenuation correction for PET/MR imaging. Semin Nucl Med 2013;43(1):45–59.
  • 29. Berker Y, Franke J, Salomon A, et al. MRI-based attenuation correction for hybrid PET/MRI systems: a 4-class tissue segmentation technique using a combined ultrashort-echo-time/Dixon MRI sequence. J Nucl Med 2012;53(5):796–804.
  • 30. Würslin C, Schmidt H, Martirosian P, et al. Respiratory motion correction in oncologic PET using T1-weighted MR imaging on a simultaneous whole-body PET/MR system. J Nucl Med 2013;54(3):464–471.
  • 31. Chawla SC, Federman N, Zhang D, et al. Estimated cumulative radiation dose from PET/CT in children with malignancies: a 5-year retrospective review. Pediatr Radiol 2010;40(5):681–686.

Article History

Received July 24, 2013; revision requested August 30; revision received December 20; accepted January 20, 2014; final version accepted April 18.
Published online: May 31 2014
Published in print: Oct 2014